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Entropy

Thermal-State Continuous-Variable Quantum Key Distribution Under the Effects of Gravity

Li Zhang, Jiannan Huang, J Zhou

Published Apr 28, 2026• 0 citations
Publisher

Abstract

Continuous-variable quantum key distribution has gradually shifted from optical fiber communication to space communication. In free-space quantum communication, the influence of gravity cannot be ignored. In light of the influence of gravity, this study assesses the efficacy of the thermal-state continuous-variable quantum key distribution (QKD) protocol in a non-inertial reference frame. This differs from the conventional scenario in an inertial reference frame, where pure vacuum Gaussian states are employed without consideration of the influence of gravity. This study examines the potential and challenges of quantum key distribution in the presence of gravitational effects. The feasibility of generating the key under the influence of gravity through the lens of quantum state transfer in a non-inertial reference system is also analyzed. It presents a comprehensive mathematical derivation and simulation of the secret key rate for maintaining a positive rate under specific conditions. Furthermore, it presents a detailed implementation plan for thermal-state quantum key distribution in a non-inertial reference frame, particularly in the context of gravity. It offers valuable insights into the performance of quantum communication in unconventional settings.

DOI
10.3390/e28050501

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Continuous-variable quantum key distribution has gradually shifted from optical fiber communication to space communication. In free-space quantum communication, the influence of gravity cannot be ignored. In light of the influence of gravity, this study assesses the efficacy of the thermal-state continuous-variable quantum key distribution (QKD) protocol in a non-inertial reference frame. This differs from the conventional scenario in an inertial reference frame, where pure vacuum Gaussian states are employed without consideration of the influence of gravity. This study examines the potential and challenges of quantum key distribution in the presence of gravitational effects. The feasibility of generating the key under the influence of gravity through the lens of quantum state transfer in a non-inertial reference system is also analyzed. It presents a comprehensive mathematical derivation and simulation of the secret key rate for maintaining a positive rate under specific conditions. Furthermore, it presents a detailed implementation plan for thermal-state quantum key distribution in a non-inertial reference frame, particularly in the context of gravity. It offers valuable insights into the performance of quantum communication in unconventional settings.
The influence of gravity on quantum key distribution cannot be ignored in practical space communication. This paper provides a thorough analysis of the effectiveness of gravity on continuous-variable quantum key distribution with discrete-modulated states. By calculating the acceleration in both inertial and non-inertial reference systems based on the discrete variable variance calculation formula, the gain coefficient is obtained. Based on this parameter, an improved protocol with a high key rate over a spatial transmission distance of 390 km is proposed, enabling the practical application of quantum key distribution techniques. The results can be used to demonstrate the performance of continuous-variable quantum key distribution with discrete modulation influenced by gravity. This paper not only extends the range of discrete modulation states, but also enhances the impact of relativistic quantum information.
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Quantum key distribution can be used to share secret keys with information-theoretic security between two legitimate partners for secure communication. In the case of satellite communication, free-space channel is the only way to transmit information, thus research on its properties is of great significance to quantum cryptographic communication. In this paper, we thoroughly analyze the influence of free-space channel fading effects on continuous variable quantum key distribution and for the first time prove that random distribution (such as Rayleigh distribution, Rice distribution and et al.) of free-space channel fading coefficients can be used to increase secret information rates and improve system stability against excess noises. Our results offer academic reference for practical applications of ground-space and space-space quantum communication and global quantum communication network.
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The domain of quantum technologies has been recently broadened to satellites orbiting the Earth. Long distance communication protocols cannot ignore the presence of the gravitational field and the effects on the quantum states. Here, we provide a general method to investigate how noninertial motion affects the performance of various quantum key distribution protocols for continuous-variable states of localized wave packets. Taking advantage of the equivalence principle, our results can be thought of as due to the gravitational field. We show that the consequences of gravity strongly depend on the configuration and the cryptographic scheme used.